A ratiometric and on–off fluorescent chemosensor for highly selective detection of Cr3 + ion based on an ICT mechanism

A ratiometric and on–off fluorescent chemosensor (PB) containing a pyrene moiety was designed and synthesized for the selective detection of trivalent chromium ion over other common metal ions using an intramolecular-charge transfer (ICT) mechanism. The fluorescence emission intensities showed a significant decrease of the emission intensity at 425 nm and formation of a new band at 594 nm upon excitation at 343 nm. A well-defined isoemissive point was observed at 564 nm with increasing Cr3 + concentration. The emission ratios (F425/F594) showed good linearity with Cr3 + concentration thereby allowing the detection of Cr3 + using a ratiometric fluorescence method with a detection limit of 0.23 μM. A Job plot indicated a 1:1 binding stoichiometry with an association constant (Ka) of 7.52 × 104 M− 1, which was further confirmed by MALDI-TOF analysis.

A ratiometric and on–off fluorescent chemosensor (PB) for Cr3 + was designed and synthesized based on an ICT mechanism. The fluorescence emission intensities showed a significant decrease at 425 nm and formation of a new band at 594 nm (λem = 343 nm) with a well-defined isoemissive point at 564 nm with increasing Cr3 + concentration. The good linearity allows the detection of Cr3 + by a ratiometric fluorescence method with a detection limit of 0.23 μM.Figure optionsDownload as PowerPoint slide